Italy's Health Minister Beatrice Lorenzin has warned of health consequences if water rationing is imposed in Rome.
Parts of Italy, including the Lazio region around Rome, are suffering from drought.
The water company that serves Rome is proposing cutting supplies for eight hours a day to 1.5 million residents.
Water utility Acea blames a decision by officials to stop it taking supplies from a nearby lake.
The authorities that run Lazio say levels in Lake Bracciano have fallen too low because of the drought and they fear an environmental disaster.